import java.util.*;
public class Main3
{
    public static void main(String[] args)
    {
        Scanner cin = new Scanner(System.in);

        int n = cin.nextInt();

        Set hash = new HashSet();

        for(int i =0;i<n;i++)
        {
            int tmp = cin.nextInt();
            hash.add(tmp);
        }
        if(hash.size()!=n)
            System.out.print("YES");
        else
            System.out.print("NO");

        cin.close();
    }
}
